GB433162A - Improvements in and relating to electric control systems - Google Patents

Abstract

433,162. Control systems for consuming devices; automatic regulation. BRITISH THOMSON-HOUSTON CO., Ltd., Crown House, Aldwych, London. March 19, 1934, No. 8601. Convention date, March 18, 1933. [Class 38 (iv)] A control system for a load circuit the current in which is controlled by a variable control voltage operating upon the saturating winding of a reactance in series with it, comprises regulating means influenced by a voltage derived from the load circuit to maintain the latter at a substantially constant relation to the control voltage. The load circuit 10 is connected in series with the winding 13<a> of a variable impedance 13 of the saturable core type, the direct current winding 13b being connected through rectifiers 14, 15 to the secondary winding of a transformer 16. The primary winding of the transformer is fed from the supply lines 11, 12, and is in series with the reactive winding of a saturable core reactance 17. The control winding 17<a> is connected between the supply line 11 and the anode 18b of a valve 18, the. cathode 18<a> of which is connected to the supply line 12. A source of variable voltage comprising solenoids 20, 21 with movable core members, has a common point 22 connected through a rectifier to the circuit of the grid 18<c> of the valve 18. The grid circuit is also connected to the load circuit through a feed back transformer 26. The feed back voltage is opposite to the polarity of the voltage supplied from the connection 22 so that the voltages of the load and the common connection 22 equalize themselves irrespective of the current (e.g. number of lamps), in the load circuit. In Fig. 2 the common point 45 of the variable voltage device is connected through a rectifying bridge 44 to the direct current winding 43<a> of the reactance 43, the reactance winding of which is fed through a rectifying bridge 42 and winding 41<b> from the supply lines 38, 40. The reactance winding 41<a> of the device 41 is in series with the primary of the transformer 37 and is connected in parallel with a further reactance 46, the D.C. winding of which is fed by the voltage across the reactance 32 which is in series with the load. Should a portion of the lamps in the load circuit burn out so that the voltage across the load circuit is increased, the voltage across the winding 32<a> will decrease. This will result in an increase in the voltage drop across the winding 46<a> and a decrease in the voltage across the transformer 37. The consequent decrease in the current through the rectifiers 33, 34 will increase the reactance of the device 32<a> and automatically restore the voltage across the load circuit 31 to its original value.